boot from usb drive

This is a pretty random question, I just couldn't find much specific info on Google. It'll tells me how to do it easy enough...

Motherboards being able to set a USB device as a boot device, how common is this? Mine can do it, can most newish computers boot straight from the device without some sort of floppy that then directs to the USB storage? If so, how old does a computer need to be before the BIOS may not support it? Not really asking for a specific reason, just occurred to me that I might be able to do some cool stuff this way